Chair with automatically movable back support

ABSTRACT

A chair with an automatically movable back, having a support, and a seat and a back installed on the support. The chair comprises a base frame coupled to a lower surface of the seat in such a way as to define a space between the base frame and the seat; a horizontal movement frame coupled to an upper surface of the base frame to be moved forwards and rearwards, connected at left and right ends thereof to a back frame which in turn is connected with the back of the chair, and having on a lower surface thereof a follower which receives force required for forward and rearward movement; a vertical movement frame which has an upper surface which is connected to the lower surface of the base frame and a lower surface which is connected to the support, and which is coupled to the support such that the vertical movement frame can slide upwards and downwards with respect to the support; and rotation force generation means installed in the vertical movement frame to transmit rotation force generated by upward and downward movement of the vertical movement frame to the follower such that the horizontal movement frame can be moved forwards and rearwards.

TECHNICAL FIELD

The present invention relates to a chair having a seat and a back, and more particularly, to a chair having an automatically movable back wherein the back of the chair can be automatically moved by a user's weight to properly support the back of the user even when the user sits on a seat without bringing his or her back into contact with the back of the chair, thereby allowing the user to have a correct sitting posture.

BACKGROUND ART

In general, a chair has a back for supporting the back of a user who sits on the chair to help the user to rest in a comfortable posture and protect the spine of the user.

It is generally not considered correct posture to sit by placing the hips on the front portion of the seat. Therefore, only when the hips are placed on the very rear portion of the seat and the back of the user is brought into close contact with and supported by the back of the chair can the spine of the user be protected from bending.

Hence, the backs of chairs have been designed in consideration of ergonomic aspects to protect the spines of users.

To this end, conventional chairs are configured in a manner such that the back of a chair can be elastically inclined rearwards, or such that the back of a chair is divided into two parts to support the back of a user on both sides of the spine to thereby define a dual back structure which improves support quality and comfort.

However, in the conventional chairs, since the back of the chair is always fixedly positioned irrespective of the position on the chair on which the user sits, if the user does not sit with correct posture, in which his or her hips are placed on the very rear portion of the seat, but sits on the front or middle portion of the seat, the back of the user is spaced apart from the back of the chair. As a consequence, because the back of the chair cannot support the back of the user, the user experiences increased fatigue, and if the incorrect posture becomes a habit, the spine can be seriously influenced, as a result of which intervertebral disc hernia may occur.

DISCLOSURE OF INVENTION Technical Problem

Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a chair with an automatically movable back wherein the back of the chair can always support the back of a user irrespective of the position where the user sits on a seat, thereby decreasing the fatigue of the user, enabling the user to assume a correct sitting posture, and preventing spinal and musculoskeletal disorders.

Technical Solution

In order to achieve the above object, according to one aspect of the present invention, there is provided a chair with an automatically movable back, having a support, and a seat and a back installed on the support, the chair comprising a base frame coupled to the lower surface of the seat in such a way as to define a space between the base frame and the seat; a horizontal movement frame coupled to an upper surface of the base frame to be moved forwards and rearwards, connected at left and right ends thereof to a back frame which in turn is connected with the back of the chair, and having on a lower surface thereof a follower which receives force required for forward and rearward movement; a vertical movement frame having an upper surface which is connected to the lower surface of the base frame and a lower surface which is connected to the support, and coupled to the support such that the vertical movement frame can slide upwards and downwards with respect to the support; and rotation force generation means installed in the vertical movement frame to transmit rotation force generated by upward and downward movement of the vertical movement frame to the follower such that the horizontal movement frame can be moved forwards and rearwards.

According to another aspect of the present invention, the support has a gas cylinder and a piston, and the vertical movement frame is slidably coupled to the piston.

According to another aspect of the present invention, the vertical movement frame comprises an upper frame and a lower frame which are connected with each other, and at least one elastic member is disposed between the upper frame and the lower frame.

According to another aspect of the present invention, the rotation force generation means comprises a fixed shaft having a lower end which is coupled to the piston and an upper end which passes through the upper frame and is formed with a meshing portion; a meshing body arranged in the upper frame to be meshed with the meshing portion such that the meshing body can be rotated by upward and downward movement of the vertical movement frame; and an intermediate element connected to the meshing body and the follower to transmit rotation force of the meshing body to the follower.

According to another aspect of the present invention, a guide cylinder is fitted around the outer surface of the lower end of the fixed shaft, the lower frame is fitted around the outer surface of the guide cylinder, and a plurality of balls is accommodated in at least one groove defined in the outer surface of the guide cylinder such that the lower frame can smoothly slide with respect to the guide cylinder.

According to another aspect of the present invention, the meshing portion and the meshing body are meshed and operated in a gear fashion.

According to another aspect of the present invention, the meshing portion comprises a vertical rack gear, and the meshing body comprises a pinion gear.

According to another aspect of the present invention, the intermediate element is directly or indirectly connected with the meshing body to rotate around a predetermined point, and is meshed with the follower to transmit rotation force thereto.

According to another aspect of the present invention, the intermediate element is coupled to a rotation support member which is connected to the shaft of the meshing body, has an arc-shaped configuration which has gear teeth formed on the outer surface thereof, and is meshed with the follower.

According to another aspect of the present invention, the follower comprises a straight horizontal rack gear.

According to another aspect of the present invention, the chair further comprises braking means for fixing the horizontal movement frame, moved together with the back, to a desired position.

According to another aspect of the present invention, the braking means comprises a plurality of rods fastened on both ends thereof to be spaced apart from the upper surface of the base frame, extending in forward and rearward directions, and defined on lower surfaces thereof with engagement grooves; and a tilting frame rotatably connected to rear left and right portions of the horizontal movement frame by a pin shaft, having the shape of a plate, and formed on a front end thereof with engagement pieces that engage into the engagement grooves of the rods, so that, when the tilting frame is rotated upwards, the engagement pieces are engaged into the engaging grooves of the rods to secure the position of the horizontal movement frame.

According to another aspect of the present invention, the tilting frame has front brackets on front left and right portions thereof adjacent to the engagement pieces, which are defined with slots, an adjustment lever is rotatably coupled through the horizontal movement frame in such a way as to pass through the slots of the front brackets, and a cam is eccentrically fastened to the adjustment lever, such that, as the adjustment lever is rotated, the cam pushes the tilting frame upwards to secure the horizontal movement frame at a desired position.

According to another aspect of the present invention, there is provided a chair with an automatically movable back, having a support, and a seat and a back installed on the support, the chair comprising a base frame coupled to the lower surface of the seat in such a way as to define a space between the base frame and the seat, and having hollow pillars which project from the lower surface of the base frame; a horizontal movement frame coupled to the upper surface of the base frame to be moved forwards and rearwards, connected at left and right ends thereof to a back frame which in turn is connected with the back of the chair, and having on the lower surface thereof a follower which receives force required for forward and rearward movement; a connection housing coupled to the support, open at an upper end thereof to define a space therein, and having slide pillars into which the hollow pillars of the base frame are respectively inserted; elastic members disposed between the hollow pillars and the slide pillars to allow the base frame to move upwards and downwards with respect to the connection housing; and rotation force generation means formed in the connection housing to transmit rotation force generated by upward and downward movement of the base frame to the follower such that the horizontal movement frame can be moved forwards and rearwards.

According to another aspect of the present invention, the rotation force generation means comprises a meshing portion fixedly installed in the connection housing and formed on the outer surface thereof with a vertically extending rack gear; a meshing body installed on support brackets which are connected to the base frame between the hollow pillars, project vertically downwards, and are meshed with the meshing portion so as to be rotated; and an intermediate element connected with the meshing body and the follower and rotated to linearly move the horizontal movement frame.

According to another aspect of the present invention, one side end of the base frame is bent to face downwards, engagement grooves are defined on the edge of the bent side end of the base frame to create prominences and depressions, a tilting frame is placed on the horizontal movement frame in such a way as to cover the horizontal movement frame and is projectedly formed with an engagement piece on a side end thereof that corresponds to the engagement grooves, and an adjustment lever is rotatably installed through side walls of the horizontal movement frame and the tilting frame and has fixed thereto an eccentric cam, such that, as the adjustment lever is rotated, the cam pushes the tilting frame upwards to engage the engagement piece into one of the engagement grooves to thereby limit the movement of the horizontal movement frame.

According to another aspect of the present invention, the connection housing is connected with the support through a connection bracket which is coupled to the support such that the connection housing is rotatably connected to the connection bracket, and an angle adjustment elastic member, which is coupled to the connection bracket, and the connection housing are linked to each other so that the connection housing can be inclined rearwards within a predetermined range.

According to another aspect of the present invention, the back of the chair is rotatably coupled to left and right portions of the back frame by way of connection shafts, an angle adjustment lever, which is defined with a plurality of fixing grooves, is coupled to an end of the connection shaft so as to be axially movable, the connection shaft projecting out of one side of the back frame, such that fixing pins, which are formed on the back frame, can be selectively locked into the respective fixing grooves to adjust the inclination angle of the back, and an elastic member is connected to a rear lower end of the back such that the elastic member is coupled to the rear portion of the back frame.

According to still another aspect of the present invention, the elastic member has one end coupled to a guide ring which is moved along a guide rod fixedly installed on the back of the chair and the other end connected to an adjustment rod which is threadedly coupled to a control rod so that the position of the adjustment rod can be changed, the control rod being detachably attached in an opening groove defined in the rear portion of the back frame.

According to a still further aspect of the present invention, the opening groove is open toward the upper surface of the back frame, such that, by pushing the control rod fitted into the opening groove and removing the control rod from the opening groove, the back can be rotated forwards around the connection shafts in such a way as to be folded.

ADVANTAGEOUS EFFECTS

Thanks to the features of the chair having an automatically movable back according to the present invention, advantages are provided in that, regardless of where a user sits on a seat, the back of the chair is automatically moved forwards to correctly support the back of the human body so that a user can sit with his or her back straightened naturally. Therefore, it is possible to sit in a correct sitting posture and protect the spine, so that spinal and musculoskeletal disorders are prevented.

Also, when compared to the conventional art, convenience is improved and costs for storing and moving the chair can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view illustrating the structure of a chair with an automatically movable back in accordance with the present invention;

FIG. 2 is a schematic side sectional view illustrating a first preferred embodiment of the present invention;

FIG. 3 is a side sectional view illustrating main parts;

FIG. 4 is a front sectional view illustrating the main parts;

FIG. 5 is a plan view illustrating the main parts;

FIG. 6 is a front view illustrating a connection shaft;

FIG. 7 is a view illustrating the assembled state of an angle adjustment lever;

FIG. 8 is a front view of the angle adjustment lever;

FIG. 9 is an exploded perspective view illustrating the main parts of a chair in accordance with a fourth embodiment of the present invention;

FIG. 10 is a sectional view illustrating the main parts in an assembled state; and

FIG. 11 is a sectional view illustrating a fifth embodiment of the present invention.

DESCRIPTION OF REFERENCE NUMERALS FOR MAIN PARTS IN DRAWINGS

-   -   100: support 120: piston     -   200: seat 300: back     -   310: back frame 320: connection shaft     -   330: angle adjustment lever     -   340: elastic members     -   400: base frame 500: horizontal movement frame     -   510: follower 600: vertical movement frame     -   610: upper frame 620: lower frame     -   700: rotation force generation means     -   710: fixed shaft     -   720: rolling element 730: intermediate element     -   740: guide cylinder 800: braking means     -   810: rod 820: tilting frame     -   830: adjustment lever 840: cam

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. It is to be readily understood that, since the drawings attached herein exemplarily embody the technical idea of the present invention, the scope of the present invention is not limited by the illustration of the drawings.

FIG. 1 is a schematic perspective view illustrating the structure of a chair with an automatically movable back in accordance with the present invention, and FIG. 2 is a schematic side sectional view illustrating a first preferred embodiment of the present invention.

As can be seen from the drawings, the present embodiment illustrates a state in which the present invention is applied to an office chair which has wheels. However, it is to be readily understood that the present invention is not limited to this particular illustration, but can be applied to a vehicle seat, etc. Basically, the chair has a support 100, and a seat 200 and a back 300 which are installed on the support 100. The support 100 can be appropriately configured depending upon the kind of chair, the installation place, etc.

One of the important features of the present invention resides in that, when a user sits on the seat 200, the back 300 is automatically moved to be brought into contact with the back of the user so that the user can sit with a correct sitting posture. To this end, the chair further has a base frame 400, a horizontal movement frame 500, a vertical movement frame 600, and rotation force generation means 700.

FIG. 3 is a side sectional view illustrating main parts, FIG. 4 is a front sectional view illustrating the main parts, and FIG. 5 is a plan view illustrating the main parts.

The base frame 400 is coupled to the lower surface of the seat 200 and is fastened to the seat 200. Actually, a space is defined between the base frame 400 and the seat 200, excluding the portions where the base frame 400 is locked to the lower surface of the seat 200 by means of bolts, etc.

The horizontal movement frame 500 is installed on the upper surface of the base frame 400. The horizontal movement frame 500 is coupled to the base frame 400 to be moved forwards and rearwards, and a back frame 310 is connected to the left and right sides of the horizontal movement frame 500. The back frame 310 is connected with the horizontal movement frame 500 in such a way as not to interfere with the seat 200, and extends above the seat 200. The back 300 is connected to the back frame 310. A follower 510 is coupled to the center portion on the lower surface of the horizontal movement frame 500 to receive force required for forward and rearward movement thereof.

In the present embodiment, as shown in the drawings, the left and right sides of the base frame 400 are bent to have a U-shaped section. In correspondence with this, a plurality of rollers ‘r’ is attached to the lower ends of the left and right sides of the horizontal movement frame 500 such that the horizontal movement frame 500 can be linearly moved along the base frame 400.

The vertical movement frame 600 is installed on the lower surface of the base frame 400, and the lower end of the vertical movement frame 600 is connected with the support 100. In particular, the vertical movement frame 600 is coupled to the support 100 such that the vertical movement frame 600 can slide upwards and downwards relative to the support 100. When a load is applied to the seat 200, the base frame 400, the horizontal movement frame 500 and the vertical movement frame 600 are lowered. Conversely, when the load applied to the seat 200 is removed, the vertical movement frame 600 is raised to its original position. At this time, the vertical movement frame 600 can be raised relative to the support 100 due to disposal of elastic members 630 between the support 100 and the vertical movement frame 600 so that, when the applied load is removed, the vertical movement frame 600 can be returned to its original position. This will be described later in detail.

If the user sits on the seat 200, the back frame 310 and the back 300, which are connected with the horizontal movement frame 500, are moved forwards to be brought into contact with the back of the user. Driving force for forward and rearward movement of the horizontal movement frame 500 is generated by the rotation force generation means 700, which is installed in the vertical movement frame 600. The rotation force generation means 700 generates rotation force in conjunction with the upward and downward movement of the vertical movement frame 600 and transmits the rotation force to the follower 510, which is provided to the horizontal movement frame 500 so that rotational movement is converted into linear movement.

The main technical characteristic of the present invention resides in that the automatic movement of the back 300 is realized through a mechanical system, more specifically, in that the rotation force generated through the upward and downward movement of the vertical movement frame 600 is transmitted to the follower 510 of the horizontal movement frame 500, and thereby the horizontal movement frame 500 is linearly moved forwards and rearwards along the base frame 400. The rotation force generation means 700, which will be described below in further detail, is only an example of realization of the linear movement of the horizontal movement frame 500, and therefore, it is to be noted that various modifications of the rotation force generation means 700 fall under the scope of the present invention as long as they can be easily accomplished by a person having ordinary knowledge in the art and they fall within the technical idea of the present invention.

In constructing the present invention, the support 100 serves as a part for supporting the load applied to the seat 200. The support 100 can be fixedly installed at a specified location on the ground, or can be coupled to a wheel frame which is provided with wheels for allowing movement.

The support 100 is constructed in the same manner as that provided in the conventional chair. Preferably, in order to permit height adjustment of a chair, the support 100 comprises a gas cylinder 110 and a piston 120. The vertical movement frame 600 is connected to the piston 120, which projects from the gas cylinder 110. Since the height adjustment mechanism of the chair is well known in the art, a detailed description thereof will be omitted herein.

In the present embodiment, the vertical movement frame 600 is divided into two parts, that is, an upper frame 610 and a lower frame 620. Elastic members 630 are disposed between the upper frame 610 and the lower frame 620 in a manner such that the lower ends of the elastic members 630 abut a fixed shaft 710 constituting the rotation force generation means 700, which will be described later. Due to the presence of the elastic members 630, if the load applied to the seat 200 is removed, the vertical movement frame 600 and the parts other than the rotation force generation means 700, which are lowered, are raised to their original positions. It is possible for the vertical movement frame 600 to be integrally constructed. In the present embodiment, the vertical movement frame 600 is divided into two parts in consideration of convenience in fabrication and assembly thereof.

The detailed structure of the rotation force generation means 700, which is installed in the vertical movement frame 600, will be explained below. The rotation force generation means 700 includes, as its main component elements, the fixed shaft 710, a meshing body 720 and an intermediate element 730. The fixed shaft 710 has a lower end which is fixed to the piston 120 and an upper end which extends through the upper frame 610. As shown in the drawings, it is preferred that the fixed shaft 710 have a large diameter portion 710 a and a small diameter portion 710 b having different diameters. A groove is defined through the large diameter portion 710 a, which constitutes the lower portion of the fixed shaft 710, and the piston 120 is fitted into the groove. The small diameter portion 710 b of the fixed shaft 710 projects through the upper frame 610, and a meshing portion 711 is formed on the upper end of the small diameter portion 710 b. The meshing portion 711 is meshed with the meshing body 720, which will be described later in detail, to allow the meshing body 720 to rotate.

The vertical movement frame 600 is coupled to the support 100 in a manner such that it can be moved upwards and downwards. In the present embodiment, to this end, a guide cylinder 740 is fitted around the outer surface of the fixed shaft 710, and the vertical movement frame 600 is fitted around the outer surface of the guide cylinder 740. The way in which the vertical movement frame 600 is slidably coupled to the support 100 can be changed in various ways. It is to be noted that the illustration is only one example thereof.

Meanwhile, in order to ensure smooth upward and downward movement of the vertical movement frame 600 (more specifically, the lower frame 620) which is fitted around the guide cylinder 740, preferably, a plurality of grooves is defined in the outer surface of the guide cylinder 740, and a plurality of balls ‘b’ is accommodated in the grooves so that sliding can be easily accomplished.

The meshing body 720, which is directly meshed with the meshing portion 711 formed on the fixed shaft 710, will be described below. The meshing body 720 is rotatably arranged in the upper frame 620 which constitutes the vertical movement frame 600. That is to say, the meshing body 720 is fitted around the horizontal shaft 781, which is installed to pass through the upper frame 610 in leftward and rightward directions, such that the meshing body 720 can be rotated around the horizontal shaft 781. The meshing body 720 is meshed with the meshing portion 711 of the fixed shaft 710, which is fixedly installed at a predetermined position, such that the meshing body 720 can be rotated by the meshing portion 711 when the vertical movement frame 600 implements vertical movement.

Preferably, the meshing body 720 and the meshing portion 711, which is formed on the upper end of the fixed shaft 710, are meshed with each other in a gear fashion. In particular, the meshing body 720 may comprise a pinion gear, and the meshing portion 711 may comprise a vertically extending rack gear. Nevertheless, since it is sufficient to generate rotation force in the meshing body 720 by way of friction between the meshing body 720 and the meshing portion 711, means other than the gear type may be employed.

When rotation force is generated in the meshing body 720 due to interaction between the meshing body 720 and the meshing portion 711, the rotation force is transmitted to the follower 510 via the intermediate element 730 which is connected with the meshing body 720, as a result of which the horizontal movement frame 500 can be linearly moved. The intermediate element 730 indicates an element which is directly or indirectly connected with the meshing body 720 and rotates along the same locus. The intermediate element 730 transmits rotation force to the follower 510 through gear meshing.

Preferably, the follower 510 comprises a horizontally extending rack gear which has a linear configuration. The intermediate element 730, which rotates along the same locus, has an arc-shaped configuration and is formed on the outer surface thereof with gear teeth which are meshed with the horizontal rack gear constituting the follower 510.

The intermediate element 730 can be directly and integrally connected to the meshing body 720, or can be coupled to a rotation support member 722 which is connected with the horizontal shaft 781 on which the meshing body 720 is installed, to transmit rotation force.

Hereinbelow, a second embodiment of the chair having an automatically movable back according to the present invention will be described below. The main technical feature of the second embodiment resides in that braking means 800 is further provided to allow the horizontal movement frame 500, which is linearly moved in a horizontal direction along the base frame 400, to be fixed at an optional position.

In the chair according to the present invention, when the user sits on the seat 200, the back 300 of the chair is moved until the back 300 is brought into contact with the back of the user. At this time, since the back 300 is connected with the horizontal movement frame 500 via the back frame 310, the back 300 pushes the back of the user when the user sits on the seat 200. However, as the case may be, it may be necessary to fix the position of the back 300 so as to prevent the back 300 from pressing the back of the user with excessive force.

The braking means 800 has, as its main component parts, rods 810 and a tilting frame 820. Each rod 810 is installed on the base frame 400. A plurality of rods 810 is provided to extend in forward and rearward directions such that they are spaced apart from the upper surface of the base frame 400, excluding both ends thereof, at which they are secured to the base frame 400. A plurality of engagement grooves 811 is defined at regular intervals on the lower surface of each rod 810. In the present embodiment, two rods 810 are provided so that balance can be maintained in the leftward and rightward directions.

The tilting frame 820 is rotatably connected to the rear left and right portions of the horizontal movement frame 500 by means of a pin shaft 821. The tilting frame 820 has the shape of a plate which covers the upper surface of the horizontal movement frame 500, and is formed on the front end thereof with engagement pieces 822 that engage into the engagement grooves 811 of the rods 810. The engagement pieces 822 are fitted around the rods 810. Before the tilting frame 820 is pivoted upwards, the tilting frame 820 can be moved along with the horizontal movement frame 500 in the forward and rearward directions. However, if the tilting frame 820 is pivoted upwards, as the engagement pieces 822 are engaged into the engagement grooves 811, forward and rearward movement of the horizontal movement frame 500 is prevented.

When the tilting frame 820 is provided, the back frame 310 is coupled to the upper surface of the tilting frame 820, and accordingly, when the horizontal movement frame 500 is moved forwards and rearwards, the back 300 can be simultaneously moved therewith. If the user initially sits on the seat 200, the back 300 is moved to be brought into close contact with the back of the user. Then, if the back 300 is slightly pushed rearwards by inclining the user's body, the tilting frame 820, which is connected with the back frame 310, is pivoted upwards, and the engagement pieces 822 are engaged into the engagement grooves 811, as a result of which further forward movement of the back 300 is prevented. In this regard, in the case where the braking means 800 is simply composed of the tilting frame 820 and the rods 810, if the user rises from the seat 200, the horizontal movement frame 500 always returns to its original position.

In the structure of the braking means 800, it is more preferred that a user be able to fix the horizontal movement frame 500 at an optional position so that the back 300 does not move even when the user rises from the seat 200. To this end, an adjustment lever 830 having a cam 840 fastened thereto is provided such that a user can selectively pivot the tilting frame 820 upwards to hold the back 300 in a fixed state.

In greater detail, front brackets 823, which are defined with track-shaped slots 824, are formed on the front left and right portions of the tilting frame 820. The adjustment lever 830 is rotatably coupled to the horizontal movement frame 500 in such a way as to pass through the slots 824 of the front brackets 823. Preferably, a handle is fastened to one end of the adjustment lever 830 to allow the user to manipulate the adjustment lever 830. Perforations, which are defined through the left and right portions of the horizontal movement frame 500 to allow the adjustment lever 830 to pass therethrough, have the sectional shape of a circle having diameter corresponding to that of the adjustment lever 830, so that the rotation of the adjustment lever 830 is not hindered. The adjustment lever 830 has the shape of an elongate rod, and the cam 840 is fastened to the adjustment lever 830 at an optional position inside the horizontal movement frame 500. The cam 840 has an eccentric configuration. In a portion which corresponds to the position of the cam 840, the horizontal movement frame 500 is partially open such that the cam 840 can project through the horizontal movement frame 500 to be brought into contact with the tilting frame 820.

As the adjustment lever 830, which passes through the horizontal movement frame 500 and the tilting frame 820, is rotated, the cam 840 upwardly pushes the tilting frame 820, which is positioned above the horizontal movement frame 500. Due to the fact that the adjustment lever 830 passes through the slots 824 which are defined through the front brackets 823 which are formed on the front left and right portions of the tilting frame 820, as force is upwardly applied to the cam 840, which is brought into contact with the tilting frame 820, only the tilting frame 820 is pivoted upwards along the slots 824. Pivotal movement of the tilting frame 820 occurs around the pin shaft 821, and the movement of the horizontal movement frame 500 is prevented due to engagement of the engagement pieces 822 in the engagement grooves 811. If the user wants to adjust the position of the back 300, the adjustment lever 830 must be rotated to release contact between the cam 840 and the tilting frame 820 to thereby return the tilting frame 820 to a horizontal state.

Hereafter, a third embodiment of the chair with an automatically movable back according to the present invention will be described below with reference to FIGS. 2 through 8. FIG. 6 is a front view illustrating a connection shaft, FIG. 7 is a view illustrating the assembled state of an angle adjustment lever, and FIG. 8 is a front view of the angle adjustment lever.

As can be seen from these drawings, the third embodiment of the present invention is characterized in that, in addition to the horizontal movement of the back 300 and the horizontal movement frame 500, the back 300 can be rotated to enable adjustment of the angle of the back 300.

In this embodiment, the back 300 of the chair is coupled to the left and right portions of the back frame 310, which is connected with the horizontal movement frame 500 or the tilting frame 820, by means of connection shafts 320 to form a rotatable structure. The connection shafts 320 provide the rotation center of the back 300. In the chair according to the present invention, the back frame 310, which is connected with the horizontal movement frame 500, is formed to extend upwards from below the seat 200 to be positioned higher than the seat 200 such that the back frame 310 can serve as an armrest. Due to this fact, the connection shafts 320 are connected to the back 300 at a position higher than the lower end of the back 300. In the case of chairs in general, the position where the back of the chair is rotated or inclined is defined to correspond to the lower end of the back. In this case, when the back is rotated or inclined, since a space is created between the back of the chair and a user's back or hips, the spine of the user is likely to be adversely influenced, thus leading to a disorder.

Conversely, in the present invention, due to the fact that the rotation point of the back 300 is positioned higher than the lower end of the back 300, that is, it corresponds to a position between the shoulder and the elbow of the user, even when the back 300 is inclined, since the portion of the back 300 positioned lower than the rotation point of the back 300 can be moved forwards to be brought into close contact with the back and the hips of the user, the problem caused in general chairs can be solved.

The connection shafts 320 are fitted from the outside of the back frame 310 into the back 300. An angle adjustment lever 330 is coupled to the connection shaft 320, which projects from either the left or the right side of the back frame 310. Alternatively, angle adjustment levers 330 may be coupled to the respective connection shafts 320, which project from both left and right sides of the back frame 310. The angle adjustment lever 330 can be axially moved relative to the connection shaft 320, and is defined with a plurality of depressed or perforated fixing grooves 331 adjacent to the edge thereof. In the present embodiment, two depressed fixing grooves 331 are oppositely defined adjacent to the edge of the angle adjustment lever 330.

Meanwhile, corresponding to the fixing grooves 331, fixing pins 311 are projectedly formed on the back frame 310, such that the fixing pins 311 can be selectively locked into the respective fixing grooves 331. Due to the fact that the angle adjustment lever 330 can be axially moved relative to the connection shaft 320, if the angle adjustment lever 330 is pulled outward, the fixing grooves 331 are released from the fixing pins 311, so that the back 300 can be rotated. Conversely, if the angle adjustment lever 330 is pushed inward toward the back frame 310, the fixing grooves 331 are coupled to the fixing pins 311, so that the back 300 cannot be rotated.

With the back 300 and the angle adjustment lever 330 connected to the connection shaft 320, if the back 300 is inclined, the angle adjustment lever 330 is also rotated in the same direction. The angle adjustment lever 330 can be axially moved with respect to the connection shaft 320 within a predetermined distance and can be integrally rotated with the connection shaft 320. In order to realize the axial movement of the angle adjustment lever 330 with respect to the connection shaft 320, as shown in FIG. 6, two guide grooves 321 are defined on the outer surface of the connection shaft 320 adjacent to the outer end thereof, and in correspondence with this, a plurality of balls 332 is accommodated in the angle adjustment lever 330 and is supported by springs 333 such that the balls 332 are biased by the springs 333 into either one of the guide grooves 321. Accordingly, as the angle adjustment lever 330 is pushed or pulled by the user, it is axially moved with respect to the connection shaft 320 between the guide grooves 321.

The angle of the fixing grooves 331 with respect to the connection shaft 320 defines the maximum angle through which the back 300 can be rotated in use of the chair. When the chair is not used, by releasing the fixing grooves 331 from the fixing pins 311, the back 300 can be completely folded.

Preferably, one end of an elastic member 340 is connected to the rear lower end of the back 300, and the other end of the elastic member 340 is connected to the rear portion of the back frame 310. As the elastic member 340, various kinds of conventional elastic members can be employed. In the present embodiment, a coil spring is employed as the elastic member 340. Due to the fact that the back 300 and the back frame 310 are connected with each other by the elastic member 340, if the user pushes and inclines the back 300 rearwards, the elastic member 340 is tensed, and returning force for returning the back 300 to the original position is applied to the back 300.

When installing the elastic member 340, while it is possible to simply connect both ends of the elastic member 340 directly to the back 300 and the back frame 310, it is more preferable to use the structure described below.

When the coil spring is employed as the elastic member 340, in order to connect the elastic member 340 to the back 300 and the back frame 310, a guide rod 341, a guide ring 342, a control rod 343 and a variable rod 344 are additionally provided. The guide rod 341 is installed on the center portion of the rear surface of the lower end of the back 300, and the guide ring 342 is slidably fitted around the guide rod 341. One end of the elastic member 340 is connected to the guide ring 342.

The control rod 343 and the variable rod 344 are used as means for connecting the other end of the elastic member 340 to the back frame 310. The control rod 343 is coupled to the rear end of the back frame 310 at a position which is in the same vertical plane as the guide rod 341. The variable rod 344 is threadedly coupled to the control rod 343, and the other end of the elastic member 340 is connected to the variable rod 344. The control rod 343 can be rotated in a state in which it is fitted into the opening groove 312 defined in the back frame 310. Since the position of the variable rod 344 can be changed by the rotation of the control rod 343, it is possible to adjust the initial elastic force of the elastic member 340.

Specifically, in the present invention, the elastic member 340 has a technical characteristic in that, as the back 300 is inclined rearwards, the guide ring 342 connected to the elastic member 340 is gradually moved upwards along the guide rod 341. In comparison with the conventional case, in which the position of one end of the elastic member, which is connected to the back 300, is fixed, since the position of one end of the elastic member 340 can be changed, assuming that the back 300 is inclined by the same angle, the force that must be applied by the user to the back 300 is not greatly increased, and the angle of the back 300 can be adjusted by the application of a small force.

When installing the control rod 343 in the opening groove 312 which is defined in the back frame 310, while it is possible to couple the control rod 343 by simply defining a hole in the back frame 310 as the opening groove 312, in the present embodiment, it is intended that the control rod 343 be able to be released from the back frame 310 as the occasion demands, so that the back 300 can be folded forward to be held in a substantially horizontal state. In the conventional art, because the back of a chair extends above the seat of the chair, when moving to a new residence or delivering or storing the chair, due to the height which is occupied by the back of the chair, inconvenience is caused and space utilization efficiency is deteriorated. However, in the present invention, since the back of the chair can be folded as the occasion demands, the operations of storing or delivering the chair can be conveniently implemented, and costs can be saved.

To this end, the opening groove 312 is defined to be open toward the upper surface of the back frame 310. The sectional shape of the opening groove 312 may be variously changed. However, in order to prevent the control rod 343 from being unintentionally released after fitting the control rod 343 into the opening groove 312, it is appropriate to provide a stopper (not shown) to the back frame 310.

When using the chair with the control rod 343 fitted into the opening groove 312, the rotation angle of the back 300 can be adjusted within the range in which the user manipulates the angle adjustment lever 330 or within a range limited by the elastic modulus of the elastic member 340. When moving to a new residence or delivering the chair, in order to decrease the space occupied by the chair, after pushing and releasing upwards the control rod 343 from the opening groove 312, by inclining the back 300 forwards around the connection shafts 320, the back 300 can be folded by 90° or more, such that the angle of the back 300 can be adjusted to an extent that the upper end of the back 300 substantially approaches the seat 200.

Hereafter, a chair in accordance with a fourth embodiment of the present invention will be described.

FIG. 9 is an exploded perspective view illustrating the main parts of a chair in accordance with a fourth embodiment of the present invention, and FIG. 10 is a sectional view illustrating the main parts in an assembled state.

In the present embodiment, as in the aforementioned embodiment, when a user sits on a seat 200, the back of the chair is moved to be brought into contact with the back of the user. In this regard, the detailed construction of the present embodiment is slightly different from that of the aforementioned embodiments.

The chair according to this fourth embodiment has, as its main component elements, a base frame 400, a horizontal movement frame 500, a connection housing 900, elastic members ‘S’, and rotation force generation means 700. Specifically, in the present embodiment, as the base frame 400 is moved upwards and downwards relative to the connection housing 900, driving force for moving the horizontal movement frame 500 is generated.

The base frame 400 is coupled to the lower surface of the seat 200 such that a space is defined between the base frame 400 and the seat 200. Two hollow pillars 450 are projectedly formed on the lower surface of the base frame 400. The partial area of the base frame 400 between the hollow pillars 450 is open. Also, more preferably, two support brackets 460, needed for installation of the rotation force generation means 700, which will be described later, are formed on the base frame 400 and extend downwards while facing each other. The support brackets 460 are formed on the opposite edges of the open area which is defined between the hollow pillars 450 of the base frame 400. The support brackets 460 can be formed by bending portions of the base frame 400 or by welding separate plates to the base frame 400.

The horizontal movement frame 500, which is to be horizontally moved, is positioned over the base frame 400. The horizontal movement frame 500 has a shape which has left and right side walls formed by bending a plate member. Suitable guide means ‘G’ are provided to allow the horizontal movement frame 500 to be linearly moved along the base frame 400. Since the structure of such guide means ‘G’ is well known in the art, a detailed description thereof will be omitted herein. A follower 510 is coupled to the lower surface of the horizontal movement frame 500. As the rotation force generated by the rotation force generation means 700, which will be described later, is transmitted to the horizontal movement frame 500 through the follower 510, the horizontal movement frame 500 can be linearly moved in a horizontal direction. In the meanwhile, it is preferred that the follower 510 comprise a linearly extending rack gear. A back frame 310 is connected to the left and right sides of the horizontal movement frame 500. It is also possible for the back frame 310 to be coupled to the upper surface of the horizontal movement frame 500 and to extend across the horizontal movement frame 500 in leftward and rightward directions. As will be described later, in the case where a tilting frame 820 is additionally provided on the horizontal movement frame 500, the back frame 310 must be connected to the tilting frame 820.

The connection housing 900 is provided below the base frame 400 in a manner such that the base frame 400 is coupled to the connection housing 900. As shown in the drawings, the connection housing 900 is open at the upper end thereof and defines a space therein. Slide pillars 910 are formed on left and right side walls of the connection housing 900. The hollow pillars 450 of the base frame 400 are inserted into respective slide pillars 910, and the elastic members ‘S’ are disposed between the hollow pillars 450 and the slide pillars 910. A conventional coil spring can be employed as the elastic member ‘S’. When the elastic member ‘S’ is inserted into the hollow pillar 450, the length of the elastic member ‘S’ becomes greater than that of the hollow pillar 450, such that the lower end of the elastic member ‘S’ is brought into contact with the bottom of the slide pillar 910. The connection housing 900 is connected to the support 100 in a fixed state, and the base frame 400 can be moved upwards and downwards relative to the connection housing 900.

The horizontal movement frame 500 is moved by the rotation force generation means 700, which is operated in response to the upward and downward movement of the base frame 400. The rotation force generation means 700 is installed in the connection housing 900. In further detail, the rotation force generation means 700 includes a meshing portion 711, a meshing body 720, and an intermediate element 730. The meshing portion 711 is fixedly installed on the bottom surface of the connection housing 900 and is brought into contact with the meshing body 720, which will be described later, to cause rotation of the meshing body 720. Preferably, the meshing portion 711 comprises a vertically extending rack gear.

The meshing body 720 to be meshed with the meshing portion 711 is provided in the connection housing 900. The meshing body 720 is installed on the support brackets 460, which are formed on the base frame 400 and extend vertically downwards. As shown in the drawings, holes are defined through the lower ends of the support brackets 460, and the meshing body 720, fitted around a horizontal shaft, is inserted through the holes. A bearing is interposed between the meshing body 720 and the horizontal shaft such that the meshing body 720 can be rotated around the horizontal shaft. The meshing body 720 comprises a gear and can be rotated because it is meshed with the meshing portion 711.

The rotation force generated in the meshing body 720 is transmitted through the intermediate element 730 to the follower 510. The intermediate element 730 is connected to the meshing body 720 and is integrally rotated therewith. In the present embodiment, the intermediate element 730 comprises an arc-shaped gear which can be directly or indirectly connected with the meshing body 720. The arc-shaped gear, serving as the intermediate element 730, is meshed with the follower 510. If the intermediate element 730 is rotated, the rotation force is transmitted to the follower 510, by which the horizontal movement frame 500 is linearly moved in the horizontal direction. The arc-shaped gear, serving as the intermediate element 730, projects through the open area defined in the base frame 400 to mesh with the follower 510.

Due to this assembly relationship, when a user sits on the seat 200, the base frame 400 including the seat 200 is lowered with respect to the fixed connection housing 900. Thereupon, as the meshing body 720 is rotated on the meshing portion 711, the meshing body 720 rotates the intermediate element 730. The intermediate element 730 transmits force to the follower 510 such that the horizontal movement frame 500 is moved to be brought into tight contact with the back of the user.

In constructing the chair having an automatically movable back in accordance with the fourth embodiment of the present invention, it is preferable to provide braking means for allowing the horizontal movement frame 500 to be fixed at a desired position desired by the user.

In order to configure the braking means, one side end of the base frame 400 is bent downwards, and a plurality of engagement grooves 811 is defined therein. The horizontal movement frame 500 is installed on the upper surface of the base frame 400, and the tilting frame 820 is additionally installed on the horizontal movement frame 500. The tilting frame 820 is located in such a way as to surround the horizontal movement frame 500. An engagement piece 822, which is to be engaged into the engagement grooves 811, is formed on and projects from one end of the tilting frame 820. Further, an adjustment lever 830 is rotatably installed through the side walls of the horizontal movement frame 500 and the tilting frame 820, and an eccentric cam 840 is fastened to the adjustment lever 830. The structure and operation of the adjustment lever 830 is the same as mentioned in the above embodiments. When the adjustment lever 830 is rotated, as the cam 840 extends through the horizontal movement frame 500, the cam 840 is brought into contact with and pushes upwards the tilting frame 820, and according to this, the engagement piece 822 is engaged into the engagement groove 811, whereby the movement of the horizontal movement frame 500 is stopped. Therefore, the user can fix the back 300 at a desired position. If the adjustment lever 830 is rotated further so that the cam 840 is not brought into contact with the tilting frame 820, the engagement piece 822 is disengaged from the engagement groove 811, and the horizontal movement frame 500 is converted to a state in which it can be moved again. In the case where the tilting frame 820 is provided, the back frame 310 is directly connected to the tilting frame 820.

Finally, a fifth embodiment of the present invention will be described. FIG. 11 is a sectional view illustrating a fifth embodiment of the present invention.

In this embodiment, even though a chair is constructed to have the same construction as the fourth embodiment, when connecting the connection housing 900 to the support 100, a connection bracket 1000 is used as an additional element. The connection bracket 1000 is positioned below the connection housing 900. The connection bracket 1000 is fixed to the support 100, and the connection housing 900 is rotatably connected to the connection bracket 1000. An angle adjustment elastic member 1100 is provided to the connection bracket 1000, and the connection housing 900 is connected to the angle adjustment elastic member 1100. As shown in the drawing, the connection housing 900 can be inclined rearwards with respect to the connection bracket 1000 within a predetermined range, to improve convenience in a situation such as when a user takes a rest.

In the fourth and fifth embodiments, in the same manner as the other embodiments, the back of the chair can be rotated with respect to the back frame, so as to be folded.

INDUSTRIAL APPLICABILITY

As is apparent from the above description, the chair with an automatically movable back according to the present invention, constructed as mentioned above, provides advantages in that, since the back of the chair is always automatically adjusted so as to be brought into close contact with the back of a user irrespective of the body condition of the user or despite the poor sitting posture of the user, the chair can be actually applied to and used in industry as a conceptually new chair.

Further, in the present invention, in addition to convenience in use, because the back of the chair can be horizontally folded, the space occupied by the chair can be reduced so as to be easily stored and moved, to thereby increase the usability of the chair.

Meanwhile, the chair with an automatically movable back according to the present invention can be applied to a variety of articles for sitting, such as chairs for home use and office use, a vehicle seat, an airplane seat, a sofa, and so forth, which can be used to seat a person. 

1. A chair with an automatically movable back, having a support, and a seat and a back installed on the support, the chair comprising: a base frame coupled to a lower surface of the seat in such a way as to define a space between the base frame and the seat; a horizontal movement frame coupled to an upper surface of the base frame to be moved forwards and rearwards, connected at left and right ends thereof to a back frame which in turn is connected with the back of the chair, and having on a lower surface thereof a follower which receives force required for forward and rearward movement; a vertical movement frame having an upper surface which is connected to a lower surface of the base frame and a lower surface which is connected to the support, and coupled to the support such that the vertical movement frame can slide upwards and downwards with respect to the support; and rotation force generation means installed in the vertical movement frame to transmit rotation force, generated by upward and downward movement of the vertical movement frame, to the follower such that the horizontal movement frame can be moved forwards and rearwards.
 2. The chair according to claim 1, wherein the support has a gas cylinder and a piston, and the vertical movement frame is slidably coupled to the piston.
 3. The chair according to claim 2, wherein the vertical movement frame comprises an upper frame and a lower frame which are connected with each other, and at least one elastic member is disposed between the upper frame and the lower frame.
 4. The chair according to claim 3, wherein the rotation force generation means comprises: a fixed shaft having a lower end which is coupled to the piston and an upper end which passes through the upper frame and is formed with a meshing portion; a meshing body arranged in the upper frame to be meshed with the meshing portion such that the meshing body can be rotated by upward and downward movement of the vertical movement frame; and an intermediate element connected to the meshing body and the follower to transmit rotation force of the meshing body to the follower.
 5. The chair according to claim 4, wherein a guide cylinder is fitted around an outer surface of the lower end of the fixed shaft, the lower frame is fitted around an outer surface of the guide cylinder, and a plurality of balls is accommodated in at least one groove defined in an outer surface of the guide cylinder such that the lower frame can smoothly slide with respect to the guide cylinder.
 6. The chair according to claim 4, wherein the meshing portion and the meshing body are meshed and operated in a gear type fashion.
 7. The chair according to claim 6, wherein the meshing portion comprises a vertical rack gear, and the meshing body comprises a pinion gear.
 8. The chair according to claim 4, wherein the intermediate element is directly or indirectly connected with the meshing body to be rotated around a predetermined point, and is meshed with the follower to transmit rotation force thereto.
 9. The chair according to claim 8, wherein the intermediate element is coupled to a rotation support member which is connected to a shaft of the meshing body, has an arc-shaped configuration having gear teeth formed on an outer surface thereof, and is meshed with the follower.
 10. The chair according to claim 4, wherein the follower comprises a straight horizontal rack gear.
 11. The chair according to claim 1, further comprising: braking means for fixing the horizontal movement frame moved with the back to an optional position.
 12. The chair according to claim 11, wherein the braking means comprises: a plurality of rods fastened on both ends thereof to be spaced apart from the upper surface of the base frame, extending in forward and rearward directions, and defined on lower surfaces thereof with engagement grooves; and a tilting frame rotatably connected to rear left and right portions of the horizontal movement frame by a pin shaft, having the shape of a plate, and formed on a front end thereof with engagement pieces to be engaged into the engagement grooves of the rods, so that, when the tilting frame is rotated upwards, the engagement pieces are engaged into the engagement grooves of the rods to secure a position of the horizontal movement frame.
 13. The chair according to claim 12, wherein the tilting frame has front brackets on front left and right portions thereof adjacent to the engagement pieces, which are defined with slots, an adjustment lever is rotatably coupled through the horizontal movement frame in such a way as to pass through the slots of the front brackets, and a cam is eccentrically fastened to the adjustment lever, such that, as the adjustment lever is rotated, the cam pushes the tilting frame upwards to secure the horizontal movement frame to an optional position.
 14. A chair with an automatically movable back, having a support, and a seat and a back installed on the support, the chair comprising: a base frame coupled to a lower surface of the seat in such a way as to define a space between the base frame and the seat, and having hollow pillars which project from a lower surface of the base frame; a horizontal movement frame coupled to an upper surface of the base frame to be moved forwards and rearwards, connected at left and right ends thereof to a back frame which in turn is connected with the back of the chair, and having on a lower surface thereof a follower which receives force required for forward and rearward movement; a connection housing coupled to the support, open at an upper end thereof to define a space therein, and having slide pillars into which the hollow pillars of the base frame are respectively inserted; elastic members disposed between the hollow pillars and the slide pillars to allow the base frame to be moved upwards and downwards with respect to the connection housing; and rotation force generation means formed in the connection housing to transmit rotation force generated by upward and downward movement of the base frame to the follower such that the horizontal movement frame can be moved forwards and rearwards.
 15. The chair according to claim 14, wherein the rotation force generation means comprises: a meshing portion fixedly installed in the connection housing and formed on an outer surface thereof with a vertically extending rack gear; a meshing body installed on support brackets which are connected to the base frame between the hollow pillars and project vertically downwards, and meshed with the meshing portion to be rotated; and an intermediate element connected with the meshing body and the follower and rotated to linearly move the horizontal movement frame.
 16. The chair according to claim 14, wherein one side end of the base frame is bent to face downwards, engagement grooves are defined in an edge of the bent side end of the base frame to create prominences and depressions, a tilting frame is placed on the horizontal movement frame in such a way as to cover the horizontal movement frame and is projectedly formed with an engagement piece on one side end thereof corresponding to the engagement grooves, and an adjustment lever is rotatably installed through side walls of the horizontal movement frame and the tilting frame and has an eccentric cam fixed thereto, such that, as the adjustment lever is rotated, the cam pushes the tilting frame upwards to engage the engagement piece into one of the engagement grooves to thereby limit movement of the horizontal movement frame.
 17. The chair according to claim 14, wherein the connection housing is connected with the support through a connection bracket which is coupled to the support such that the connection housing is rotatably connected to the connection bracket, and an angle adjustment elastic member, which is coupled to the connection bracket, and the connection housing are linked with each other so that the connection housing can be inclined rearwards within a predetermined range.
 18. The chair according to claim 1, wherein the back of the chair is rotatably coupled to left and right portions of the back frame by way of connection shafts, an angle adjustment lever, which is defined with a plurality of fixing grooves, is axially movably coupled to an end of the connection shaft, which projects out of one side of the back frame, such that fixing pins, which are formed on the back frame, can be selectively locked into the respective fixing grooves to adjust an inclination angle of the back, and an elastic member is connected to a rear lower end of the back such that the elastic member is coupled to a rear portion of the back frame.
 19. The chair according to claim 18, wherein one end of the elastic member is coupled to a guide ring which is moved along a guide rod fixedly installed on the back of the chair, and another end is connected to an adjustment rod which is threadedly coupled to a control rod so that the adjustment rod can be changed in its position, the control rod being detachably attached in an opening groove defined in the rear portion of the back frame.
 20. The chair according to claim 19, wherein the opening groove is open toward an upper surface of the back frame, such that, by pushing the control rod fitted into the opening groove and removing the control rod from the opening groove, the back can be rotated forwards around the connection shafts in such a way as to be folded. 